Obstructive sleep apnea (OSA) affects over 2% of the adult population in the United states and is associated with significant neurobehavioral and cardiovascular morbidities. The morbidities of OSA relate at least in part to sleep fragmentation and intermittent hypoxia, both consequences of sleep- related collapse of the upper airway. In humans with OSA, there is significant variance in the manifestation of both the neurobehavioral and cardiovascular consequences. This variance in morbidity is only partially explained by the severity of disease. These investigators believe that vulnerability tot he morbidities of OSA is, in part, genetically-determined. For this proposal, they will focus on the substantial neurobehavioral consequences of sleep apnea. To begin to determine the genetic mechanisms contributing to the differential vulnerabilities, they will look separately at sleep fragmentation and chronic intermittent hypoxia (CIH) responses in inbred strains of mice. They will first expand the phenotypical response to sleep disruption to include, not only electroencephalographic changes, but also to characterize the neurobehavioral responses: sleepiness, changes in motor activity, learning, short and long term memory, vigilance and recovery for each of these parameters following exposure to sleep fragmentation or CIH. Responses to CIH will be characterized in the same manner. A high throughput screening algorithm will be validated against the full phenotypic responses to detect not only mutant sleep responses but mutant neurobehavioral responses characteristic of OSA. Therefore, this work provides an essential foundation for determining gene function in the susceptibility of sleepiness, impaired cognation and behavioral responses caused by obstructive sleep apnea. (End of Abstract.)